Systematic review of the survival rate and the incidence of biological, technical, and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of 5 years

Artificial Intelligence in Fractured Dental Implant Detection and Classification: Evaluation Using Dataset from Two Dental Hospitals

Fracture of a dental implant (DI) is a rare mechanical complication that is a critical cause of DI failure and explantation. The purpose of this study was to evaluate the reliability and validity of a three different deep convolutional neural network (DCNN) architectures (VGGNet-19, GoogLeNet Inception-v3, and automated DCNN) for the detection and classification of fractured DI using panoramic and periapical radiographic images. A total of 21,398 DIs were reviewed at two dental hospitals, and 251 intact and 194 fractured DI radiographic images were identified and included as the dataset in this study. All three DCNN architectures achieved a fractured DI detection and classification accuracy of over 0.80 AUC. In particular, automated DCNN architecture using periapical images showed the highest and most reliable detection (AUC = 0.984, 95% CI = 0.900–1.000) and classification (AUC = 0.869, 95% CI = 0.778–0.929) accuracy performance compared to fine-tuned and pre-trained VGGNet-19 and GoogLeNet Inception-v3 architectures. The three DCNN architectures showed acceptable accuracy in the detection and classification of fractured DIs, with the best accuracy performance achieved by the automated DCNN architecture using only periapical images.

Randomized controlled clinical trial comparing implant sites augmented with a volume-stable collagen matrix or an autogenous connective tissue graft: 3-year data after insertion of reconstructions

AIM

To assess mid-term clinical, radiographic and profilometric outcomes at implant sites, previously grafted with a volume-stable collagen matrix (VCMX) or an autogenous subepithelial connective tissue graft (SCTG).

METHODS

VCMX or SCTG were randomly applied to single implant sites in 20 patients. Following abutment connection and insertion of final reconstructions (baseline), patients were re-examined at 6 months (6M), at 1 year (FU-1) and at 3 years (FU-3). Measurements included the following: clinical data, radiographic measurement of first bone to implant contact (fBIC), soft tissue thickness and volumetric outcomes. Non-parametric tests and estimates were applied for the statistical analysis.

RESULTS

The median buccal mucosal thickness increased by 0.5 mm (Q1: -0.5; Q3: 1.25) (VCMX) (p = .281) and by 0.8 mm (Q1: 0.0; Q3: 2.5) (SCTG) (p = .047) between BL and FU-3 (intergroup p = .303). The profilometric changes of the buccal soft tissues demonstrated a median decrease between BL and FU-3 of -0.2 mm (Q1: -0.5; Q3: -0.1) (p = .039) for VCMX and a decrease of -0.1 mm (Q1: -0.8; Q3: 0.1) (p = .020) for SCTG, respectively (intergroup p = .596). Peri-implant soft tissues and bone levels remained healthy throughout the entire study period. PROMs did not show any significant differences between the groups nor significant changes over time.

CONCLUSION

Minimal changes of the peri-implant tissue contour as well as of the soft tissue thickness were observed at implant sites previously grafted with VCMX or SCTG.

How old is old for implant therapy in terms of implant survival and marginal bone levels after 5-11 years?

Aim

To evaluate implant survival and marginal bone levels (MBL_evel) at least 5 years after implant installation in patients ≥65 years old.

Methods

Patient records were screened retrospectively for the following inclusion criteria: (1) ≥65 years of age at the time of implant installation, and (2) ≥5‐year radiographic follow‐up or registered implant loss. Association between patient‐ and implant‐related data with radiographically assessed data [i.e. implant survival, mean MBL_evel (i.e. average of mesial and distal level) and maximum marginal bone loss (i.e. either mesial or distal loss; maximum MBL_oss)] were statistically evaluated by mixed effects multi‐level regression models.

Results

Two‐hundred‐eighteen implants in 74 patients were included with a mean follow‐up of 6.2 years (range: 5 to 10.7 years); four early and six late implant losses have been registered (implant survival rate: 95.4%). Mean MBL_evel and maximum MBL_oss was 1.24 ± 0.9 mm and 1.48 ± 1.0 mm, respectively. Maximum MBL_oss < 2 mm, 2 to 5 mm and ≥5 mm was found in 70.7, 28.8 and 0.5% of the implants, respectively. For both, mean MBL_evel and maximum MBL_oss, age presented a slightly protective effect (mean MBL_evel: Coef. −0.041, p = .016; maximum MBL_oss: Coef. −0.045, p = .014).

Conclusion

The high implant survival rate (95.4%), low mean MBL_evel (1.24 mm) and low frequency of maximum MBL_oss ≥ 5 mm (0.5%) observed herein after 5 to 11 years follow‐up suggest that older age should not be considered as a limiting factor for implant treatment.

Natural teeth and implant-retained prosthesis in treated periodontitis subjects

History of periodontal disease is a risk factor for the development of peri-implantitis. Implant treatment in susceptible patients should be followed by adequate periodontal treatment and stringent supportive programs. The assessment of the patient needs to be carefully evaluated before the procedure for implants. The risk associated with the sites to be treated requires evaluation with regular visits. The completion of treatment will still require committed follow-up visits with checks for pockets, bone loss, and plaque scores around implant-retained prosthesis as well as complete dentition. In our report, we describe in detail the reconstruction of lost dentition with implants in treated periodontitis subjects. The patients are still being followed with regular recall programs.

Prosthodontic Principles in Dental Implantology: Adjustments in a Coronavirus Disease-19 Pandemic-Battered Economy

More patients are requesting fixed prosthesis to replace missing teeth. More than 5 million dental implants are placed annually in the United States. This number will decrease in 2020 owing to the coronavirus disease-19 pandemic. The edentulous patient has a decreased quality of life. Prosthodontic rehabilitation/reconstruction of edentulism improves overall quality of life. Patient-reported outcome measures are subjective reports of patients' perceptions of their oral health status and the impact that it has on their quality of life. This chapter contains a variety of prosthodontic principles for the reader to help satisfy the needs and expectations of the patient.

A Pilot Study with Randomised Controlled Design Comparing TiZr Alloy Dental Implants to Ti Implants

Objectives

Evidence on the clinical performance of recently introduced dental implants in titanium-zirconium alloy is sparse. The aim of the present pilot study with randomized controlled design is to compare changes in supporting structures around dental titanium-zirconium alloy implants to commercially pure titanium implants.

Material and Methods

The present material includes consecutive patients referred to a specialist clinic in Sweden. Two patient groups treated with dental implants in two different materials - titanium (Ti) and titanium-zirconium (TiZr) - were defined after block randomisation for smoking. In total, 40 implants installed in 21 patients were available for one-year follow-up. Marginal bone level, soft tissue height and width of keratinised mucosa were registered at baseline and at one-year follow-up.

Results

At implant level, the test group (TiZr) yielded significant marginal bone loss (P < 0.001) after one year. Additionally, marginal bone loss after one year was significantly higher for TiZr implants (P < 0.001) as compared to traditional Ti implants. Soft tissue dimensions were stable throughout the evaluation time for both implant materials.

Conclusions

One-year results indicate more pronounced initial marginal bone loss for dental implants in titanium-zirconium alloy as compared to implants made of commercially pure titanium.

Interproximal contact loss between implant-supported restorations and adjacent natural teeth: A retrospective cross-sectional study of 83 restorations with an up to 10-year follow-up

STATEMENT OF PROBLEM

Interproximal contact loss between implant-supported restorations and adjacent natural teeth is a frequently encountered complication that could negatively affect surrounding tissues and/or patient satisfaction with treatment. The effect of interproximal contact loss on peri-implant tissue health and patient awareness of food impaction is currently unknown.

PURPOSE

The purpose of this retrospective cross-sectional study was to explore the effect of interproximal contact loss on peri-implant tissue health and determine whether interproximal contact loss leads to increased patient awareness of food impaction around the affected area. This study also aimed to identify whether specific patient or local factors could cause interproximal contact loss.

MATERIAL AND METHODS

Eighty-three participants with posterior single-unit implant-supported restorations were examined. The mean follow-up time after prosthesis insertion was 4 ±2.2 years (range 4 months to 10.6 years). Interproximal contacts were evaluated by using waxed dental floss. Patient age, sex, implant location, opposing tooth status, presence of endodontically treated adjacent tooth, and regular use of an occlusal device at night were recorded. Peri-implant probing depths and the presence of bleeding on probing were also recorded. Each participant was asked to indicate whether they had noticed increased food impaction around their implant-supported restoration. Statistical analysis included nonparametric Mann-Whitney U tests, the Spearman rank-order correlation, the Pearson chi-squared tests, and the paired t test (α=.05).

RESULTS

Among all examined mesial contacts, 34.1% were recorded as open, with an overall mesial interproximal contact loss (open and loose contacts combined) incidence of 48.8%. Restorations placed in premolar sites exhibited significantly tighter mesial interproximal contacts compared with those placed in molar sites (U=566, P=.041). A significant negative correlation was found between follow-up time after insertion and mesial contact tightness (r_s=-0.226, P=.041).

CONCLUSIONS

Interproximal contact loss appears to increase over time, with more surfaces being affected after longer periods of service. This study did not find an association between interproximal contact loss and peri-implant inflammation as measured by bleeding on probing, with the exception of the distolingual implant surface. Participants with interproximal contact loss were more aware of food impaction around their implant crown. Use of an occlusal device at night did not prevent interproximal contact loss.

Thermal effects of various drill materials during implant site preparation-Ceramic vs. stainless steel drills: A comparative in vitro study in a standardised bovine bone model

OBJECTIVES

The aim of this study was to evaluate thermal effects of ceramic and metal implant drills during implant site preparation using a standardised bovine model.

MATERIAL AND METHODS

A total of 320 automated intermittent osteotomies of 10- and 16-mm drilling depths were performed using zirconium dioxide-based and stainless steel drills. Various drill diameters (2.0/ 2.2, 2.8, 3.5, 4.2 mm ∅) and different cooling methods (without/ with external saline irrigation) were investigated at room temperature (21 ± 1°C). Temperature changes were recorded in real time using two custom-built multichannel thermoprobes in 1- and 2-mm distance to the osteotomy site. For comparisons, a linear mixed model was estimated.

RESULTS

Comparing thermal effects, significantly lower temperatures could be detected with steel-based drills in various drill diameters, regardless of drilling depth or irrigation method. Recorded temperatures for metal drills of all diameters and drilling depths using external irrigation were below the defined critical temperature threshold of 47°C, whereas ceramic drills of smaller diameters reached or exceeded the harmful temperature threshold at 16-mm drilling depths, regardless of whether irrigation was applied or not. The results of this study suggest that the highest temperature changes were not found at the deepest point of the osteotomy site but were observed at subcortical and deeper layers of bone, depending on drill material, drill diameter, drilling depth and irrigation method.

CONCLUSIONS

This standardised investigation revealed drill material and geometry to have a substantial impact on heat generation, as well as external irrigation, drilling depth and drill diameter.

Risk factors for abutment and implant fracture after loading

PURPOSE

Implant component fractures are one of the most serious complications in implant treatment. With a better understanding of the risk factors for fracture in the preoperative, surgery, superstructure, and post-loading phases of implant treatment, low-risk treatment could reduce implant component fractures, leading to a better prognosis. The aim of this study was to clarify the risk factors for abutment and implant fractures that occur after loading, and to perform a retrospective, approximately 10-year follow-up study to explore the risk factors in each treatment phase.

METHODS

Subjects were fitted with an implant prosthesis between January 2008 and December 2009. In total, 1,126 Ankylos implants in 430 patients were included for analysis. Binary logistic regression analysis was performed to extract factors related to non-fracture and fracture of the abutment or implant as a dependent variable.

RESULTS

Gender (OR = 3.466, 95% CI 1.296-9.268, P = 0.013), gonial angle (OR = 3.420, 95% CI 1.308-8.945, P = 0.012), and splinting status of the superstructure (OR = 4.456, 95% CI 1.861-10.669, P = 0.001) were identified as significant risk factors.

CONCLUSION

The risk of fracture is increased in males, especially those with a mandibular angle of less than 120° on panoramic radiographs, and those with a non-splinted superstructure.

Patient-reported oral hygiene and implant outcomes in general dental practice

BACKGROUND

This study investigated the possible correlations between patient-performed implant hygiene and peri-implant success and disease, as well as patient-reported outcomes, in a community-based cohort.

METHODS

Fifty-one patients (78 implants) from two private general practices were surveyed on their dental implant treatment history, oral hygiene instructions (OHI) received, home hygiene habits and current implant concerns. Their dentition, plaque/calculus scores and clinical implant parameters were examined. Correlations between hygiene habits, risk factors, implant success and peri-implant disease rates were assessed.

RESULTS

Implants had a patient-reported mean time in function of 6.7 years. Floss (74.4%), interdental brushes (IDB) (44.9%) and mouthwash (39.7%) were commonly used, while 7.7% of implants were only cleaned by brushing. Over half (56.4%) of implants fulfilled the success criteria, 61.5% had peri-implant health, 24.4% had mucositis and 7.7% had peri-implantitis. Only brushing (P < 0.001) and detectable plaque/calculus (P < 0.001) were significantly associated with more peri-implant disease. Local prosthetic factors affecting cleaning accessibility significantly reduced implant success (P < 0.001). Patients reported mixed recall of implant OHI, 7.7% of implants were aesthetically unsatisfactory and 9.0% had peri-implant symptoms.

CONCLUSIONS

Lack of interproximal cleaning and the presence of plaque/calculus were significantly associated with peri-implant disease in a community-based general practice setting, and patients reported mixed recall of OHI.

Treatment of Full and Partial Arches with Internal-Conical-Connection Dental Implants: Clinical Results after 5 Years of Follow-Up

The aim of the present investigation is to evaluate the implant therapy outcomes over a period of 5 years and to analyze several patient risk factors influencing the stability of the peri-implant tissues. Seventy-eight patients were consecutively treated between 2009 and 2017 and restored with implant-supported fixed prostheses. The following inclusion criteria were considered: partial or complete edentulism; residual bone volume of at least 3.3 mm in diameter and 8 mm in length; a favorable relationship between maxilla and mandible; at least a minimum 5 year follow-up for each implant included in the statistical analysis. Intraoral radiographs were taken at implant loading and every 12 months during the follow-up visits. They were subsequently stored on a personal computer and analyzed to determine the changes in bone level. Seventy-eight patients receiving 209 implants completed a minimum follow-up period of 5 years. One-hundred dental implants were inserted in the maxilla while 109 were placed in the mandible. Eleven (14.1%) out of 78 treated patients who received 29 (13.9%) dental implants were considered as drop-outs. On the whole, peri-implantitis was diagnosed in three implants. The average final pocket probing depth at implant level was 2.5 ± 1.2 mm. The average final bone loss after 5 years was 0.3 ± 0.4 mm, both at the mesial and distal aspect of the implant. The effects of the prosthesis type, sex and implant site did not statistically influence the marginal bone loss; on the contrary, a statistically significant difference regarding marginal bone loss was detected between smoker and non-smoker patients (p = 0.021). Implants with internal-conical abutment connection showed stable peri-implant bone levels at the medium-term follow-up. Nevertheless, further prospective long-term clinical studies are necessary to confirm these data.

Immediate placement of single implants with or without immediate provisionalization in the maxillary aesthetic region: A 5-year comparative study

Aim

To compare marginal bone level changes around immediately placed and immediately provisionalized implants with immediately placed and delayed provisionalized implants in the aesthetic region after five years of function.

Materials and Methods

Forty patients with a failing tooth in the maxillary anterior region were randomly assigned immediate implant placement with immediate (Group A: n = 20) or delayed (Group B: n = 20) provisionalization. Definitive crown placement occurred three months after provisionalization. The primary outcomes were changes in marginal bone level. In addition, survival rates, buccal bone thickness, soft peri‐implant tissues, aesthetics and patient‐reported outcomes were assessed.

Results

After 5 years, the mean mesial and distal marginal bone level changes were 0.71 ± 0.68 mm and 0.71 ± 0.71 mm, respectively, in group A and 0.49 ± 0.52 mm and 0.54 ± 0.64 mm, respectively, in group B; the difference between the groups was not significant (p = .305 and p = .477, respectively). Implant and restoration survivals were 100%. No clinically relevant differences in buccal bone thickness or in mid‐facial peri‐implant mucosal level, aesthetic and patient outcomes were observed.

Conclusions

The mean marginal bone level changes following immediate implant placement and provisionalization were comparable with immediate implant placement and delayed provisionalization. (www.isrctn.com: ISRCTN57251089 and www.trialregister.nl: NL8255).

Influence of abutment angulation on loss of prosthetic abutment torque under mechanical cycling

STATEMENT OF PROBLEM

Internal conical connections provide mechanical stability for the prosthetic abutment and implant connection. However, some clinical situations require the use of angled prosthetic abutments that may increase stress on supportive implants by difference force vectors under cyclic loading.

PURPOSE

The purpose of this in vitro study was to measure the screw loosening values of prosthetic abutments with internal conical connections (indexed and nonindexed) having different angles under mechanical cycling.

MATERIAL AND METHODS

Thirty-six implants (4.0×13 mm, Titamax) with internal conical connections and their respective universal prosthetic abutments (n=36, 3.5×3.3 mm) were divided into indexed and nonindexed groups (n=18) with abutment inclinations of 0 (straight), 17, and 30 degrees. An insertion torque of 15 Ncm was applied according to the manufacturer's specifications. The specimens underwent fatigue testing of 500 000 cycles at a frequency of 2 Hz with a dynamic compressive load of 120 N at an angle of 30 degrees. The detorque values were measured by using a digital torque meter and tabulated for statistical analyses.

RESULTS

The specimens with indexed abutments had mean ±standard deviation detorque values of 6.72 ±2.29 Ncm under mechanical cycling, whereas those with nonindexed abutments had values of 8.98 ±1.84 Ncm. In the indexed group, the lowest detorque value was observed for abutments at 30 degrees compared with the straight group (P<.05). As for nonindexed abutments, similar detorque values were observed after increasing the abutment inclination (P>.05).

CONCLUSIONS

A decrease in detorque values in the indexed abutments related to their inclination was found under mechanical cycling, whereas the prosthetic abutments with 30 degrees of angulation had the lowest values. No decrease was found in the nonindexed abutments.

Fracture strength of various titanium-based, CAD-CAM and PFM implant crowns

OBJECTIVE

CAD-CAM has dramatically advanced dental restorative procedures to include implant-supported crowns. The purpose of this study was to compare the fracture resistance following mechanical loading and thermocycling of various screw-retained and cement-retained ceramic and polymethylmethacrylate material combinations using the TiBase abutment compared to PFM implant-supported crowns.

OVERVIEW

Twelve implant restorations were fabricated for each of eight groups. Three groups were screw-retained and five groups were cement-retained implant restorations. The ceramic and polymethylmethacrylate restorations were fabricated on the TiBase abutment while the PFM restorations were fabricated on an UCLA abutment. Data were analyzed with a one way Analysis of Variance and Tukey's post-hoc test to evaluate the effect of abutment and crown type on fracture load (alpha = 0.05). A significant difference was found in the maximum fracture load between groups (P < 0.001).

CONCLUSIONS

The screw-retained implant restorations demonstrated higher fracture loads than their cement-retained counterparts. The TiBase abutment compared favorably to the UCLA abutment.

CLINICAL SIGNIFICANCE

The TiBase abutment is a titanium insert which combines the esthetics of a ceramic abutment with the mechanical properties of a titanium abutment and should be considered a viable clinical alternative to the conventional implant-supported PFM crown based on theses in vitro results and in context of in vivo studies. The lithium disilicate hybrid abutment/crown implant-supported restoration utilizing the TiBase abutment may be an ideal clinical choice due to simplicity, single appointment CAD-CAM, and esthetics.

Narrow-diameter implants versus regular-diameter implants for rehabilitation of the anterior region: a systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to evaluate studies comparing implant survival rates, marginal bone loss (MBL), and mechanical and biological complication rates between narrow-diameter implants (NDIs) and regular-diameter implants (RDIs) used for oral rehabilitation in the anterior region. The review was conducted according to the PRISMA checklist. Two independent reviewers performed a comprehensive search of the PubMed/MEDLINE, Embase, Scopus, and Cochrane Library databases for studies published until May 2020. A total of 843 implants (484 NDIs and 359 RDIs) were included. No significant difference in implant survival rate (risk difference (RD) 0.01, 95% confidence interval (CI) -0.01 to 0.03; P=0.34), MBL (standardised mean difference -0.51mm, 95% CI -1.29 to 0.26mm; P=0.19), mechanical complications (RD 0.01, 95% CI -0.02 to 0.04; P=0.40), or biological complications (RD 0.01, 95% CI -0.09 to 0.11; P=0.85) was found between the implant groups. Within the limitations of this study, it is concluded that NDIs are an effective alternative to RDIs due to similar survival rates, MBL, and mechanical and biological complication rates. However, future studies are highly encouraged due to the small number of interventional studies on this topic.

Evaluation of Milled Titanium versus Laser Sintered Co-Cr Abutments on the Marginal Misfit in Internal Implant-Abutment Connection

The precision of fit at the implant-abutment connection is an important criterion for the clinical success of restorations and implants. Several factors are involved among which are the abutment materials and manufacturing techniques. The aim of this study was to investigate the effect of two materials and methods of manufacturing implant abutments, milled titanium versus laser sintered Co-Cr, on the marginal misfit at the implant-abutment interface. Scanning electron microscopes (SEM) were used to geometrically measure the marginal vertical discrepancy of a total of 80 specimens, classified into eight categories, according to the implant system and abutment. The data were statistically analyzed by Student’s paired t test, one-way and two-way ANOVA with the Bonferroni-Holm correction at the significance level of p = 0.05. Milled titanium abutments demonstrated the lowest misfit values in the implant systems analyzed. The marginal fit of all the groups was within the clinically acceptable range for implant prostheses.

Biomechanical stress and microgap analysis of bone-level and tissue-level implant abutment structure according to the five different directions of occlusal loads

PURPOSE

The stress distribution and microgap formation on an implant abutment structure was evaluated to determine the relationship between the direction of the load and the stress value.

MATERIALS AND METHODS

Two types of three-dimensional models for the mandibular first molar were designed: bone-level implant and tissue-level implant. Each group consisted of an implant, surrounding bone, abutment, screw, and crown. Static finite element analysis was simulated through 200 N of occlusal load and preload at five different load directions: 0, 15, 30, 45, and 60°. The von Mises stress of the abutment and implant was evaluated. Microgap formation on the implant-abutment interface was also analyzed.

RESULTS

The stress values in the implant were as follows: 525, 322, 561, 778, and 1150 MPa in a bone level implant, and 254, 182, 259, 364, and 436 MPa in a tissue level implant at a load direction of 0, 15, 30, 45, and 60°, respectively. For microgap formation between the implant and abutment interface, three to seven-micron gaps were observed in the bone level implant under a load at 45 and 60°. In contrast, a three-micron gap was observed in the tissue level implant under a load at only 60°.

CONCLUSION

The mean stress of bone-level implant showed 2.2 times higher than that of tissue-level implant. When considering the loading point of occlusal surface and the direction of load, higher stress was noted when the vector was from the center of rotation in the implant prostheses.

Effect of crown-to-implant ratio on the marginal bone level changes and implant survival - A systematic review and meta-analysis

The purpose of the systematic review and meta-analysis was to analyze the existing evidence regarding the effect of crown-to-implant ratio (CIR) on the peri-implant crestal bone level change and implant survival. Randomized controlled clinical trials, prospective as well as retrospective studies with a minimum follow-up period of 12 months and 10 patients per group were included for this systematic review. Statistical analysis was performed to determine CIR effects on the peri-implant marginal bone level changes and implant survival. A total of 28 articles (14 prospective studies and 14 retrospective studies) from a database of 201 articles, with 2097 patients and 4350 implants, were included. A mean CIR ranging from 0.6 to 2.44 was presented by the study groups. A weighted mean implant loss of 0.19% per year and peri-implant marginal bone level change of 0.63 mm ± 0.55 over 46.8 ± 5.2 months was calculated from the included studies. The peri-implant marginal bone level change (p = 0.155) and the rate of implant loss (p = 0.245) showed a statistically insignificant difference between implant restorations of a high (>1.5:1) and low (<1.5:1) CIR. Within its limitations, this review concludes that a high (>1.5:1) or a low (<1.5:1) CIR does not significantly affect the peri-implant marginal bone level change and implant survival rate. However, until further evidence becomes available, extrapolation to long term clinical success cannot be ascertained.

Contour changes of peri-implant tissues are minimal and similar for a one- and a two-piece implant system over 12 years

Objectives

To assess contour changes of peri-implant tissues comparing a one- and a two-piece dental implant system over 12 years.

Materials and methods

Patients seeking implant therapy were enrolled and randomly allocated to receive implants (a one-piece (STM) or a two-piece (BRA) system). Impressions were taken at the time of insertion of the final reconstruction (BL), after 1 year (FU-1), 5 years (FU-5), and at 12 years (FU-12). Thirty patients were included in the analysis (STM, 16; BRA, 14). Digital scans of casts were superimposed and analyzed in an image analysis program. Measurements included changes of the crown height, contour changes on the buccal side of the implants and the contralateral teeth (control).

Results

Contour changes at implant sites revealed a loss of − 0.29 mm (STM) and − 0.46 mm (BRA) during an observation period of 12 years. Contour changes at the corresponding tooth sites amounted to − 0.06 mm (STM) and − 0.12 mm (BRA) during the same time period. The implant crown gained 0.25 mm (STM) and 0.08 mm (BRA) in height due to recession of the marginal mucosa. The corresponding gain in crown height at the contralateral tooth sites amounted to 0.36 mm (STM) and 0.10 mm (BRA). Interproximal marginal bone level changes measured − 0.28 mm (STM) and − 1.11 mm (BRA). The mean BOP amounted to 38.8% (STM) and 48.7% (BRA) at the 12-year follow-up (FU-12).

Conclusion

Minimal changes of the peri-implant soft tissue contour were observed at implant sites over the period of 12 years irrespective of the use of a one- or a two-piece implant system. The differences between the implant sites and corresponding teeth were clinically negligible.

Clinical relevance

Peri-implant soft tissue stability is of high clinical relevance when monitoring dental implant sites on the long run. Clinical data on the extent of soft tissue changes around different implant systems are scarce. The present RCTs demonstrate minimal changes of the peri-implant soft tissue contour 12 years after implant insertion independent of the use of a one- or a two-piece implant system.

Factors Affecting Implant Failure and Marginal Bone Loss of Implants Placed by Post-Graduate Students: A 1-Year Prospective Cohort Study

Statement of the problem: Most of the clinical documentation of implant success and survival published in the literature have been issued by either experienced teams from university settings involving strict patient selection criteria or from seasoned private practitioners. By contrast, studies focusing on implants placed and rehabilitated by inexperienced post-graduate students are scarce. Purpose: To record failure rates and identify the contributing factors to implant failure and marginal bone loss (MBL) of implants placed and rehabilitated by inexperienced post-graduate students at the one-year follow-up. Material and Methods: A prospective cohort study was conducted on study participants scheduled for implant therapy at the International University of Catalonia. An experienced mentor determined the treatment plan in accordance with the need of each participant who signed an informed consent. All surgeries and prosthetic rehabilitation were performed by the post-graduate students. Implant failure rate, contributors to implant failure, and MBL were investigated among 24 variables related to patient health, local site, and implant and prosthetic characteristics. The risk of implant failure was analyzed with a simple binary logistic regression model with generalized equation equations (GEE) models, obtaining unadjusted odds ratios (OR). The relationship between MBL and the other independent variables was studied by simple linear regression estimated with GEE models and the Wald chi² test. Results: One hundred and thirty dental implants have been placed and rehabilitated by post-graduate students. Five implants failed before loading and none after restoration delivery; survival and success rates were 96.15% and 94.62%, respectively. None of the investigated variables significantly affected the implant survival rate. At the one-year follow-up, the mean (SD) MBL was 0.53 (0.39) mm. The following independent variables significantly affected the MBL: Diabetes, implant depth placement. The width of keratinized tissue (KT) and probing depth (PD) above 3 mm were found to be good indicators of MBL, with each additional mm of probing depth resulting in 0.11 mm more MBL. Conclusion: The survival and success rates of dental implants placed and rehabilitated by inexperienced post-graduate students at the one-year follow-up were high. No contributing factor was identified regarding implant failure. However, several factors significantly affected MBL: Diabetes, implant depth placement, PD, and width of KT. Clinical Implications: Survival and success rates of dental implants placed and rehabilitated by inexperienced post-graduate students were high at the one-year follow-up, similar to experienced practitioners. No contributing factors were identified regarding implant failure; however, several factors significantly affected MBL: Diabetes, implant depth placement, PD, and KM.

Dental Implant Failure Rate and Marginal Bone Loss in Transplanted Patients: A Systematic Review and Meta-Analysis

This systematic review investigates the failure rate and marginal bone loss (MBL) of dental implants placed in patients undergoing solid-organ transplant (SOT) compared to healthy controls. Three databases (PubMed, Web of Sciences, and the Cochrane Library) were searched up to June 2020 (PROSPERO CRD42019124896). Case-control and cohort studies reporting data failure rate and marginal bone loss (MBL) of dental implants placed in SOT patients were included. The risk of bias of observational studies was assessed through the Newcastle-Ottawa Scale (NOS). Four case-control studies fulfilled the inclusion criteria; all had low risk of bias. Meta-analyses revealed consistently lower implant failure rate than control populations at patient and implant levels. SOT patients had a significant difference of −18% (p-value < 0.001) MBL compared to healthy patients. SOT status poses no serious threat to implant survival. Overall, this group of patients presented lower levels of dental implant failure rate and marginal bone loss compared to otherwise healthy patients. Further intervention trials with larger sample size and longer follow-ups are necessary to confirm these summarized results.

Biomechanical planning for minimally invasive indirect restorations

This paper explores the planning and execution of indirect partial-coverage restorations and will outline practical recommendations for maximising the outcomes for minimally invasive (MI) approaches to indirect restorations, with a special focus on vital teeth, endodontically-treated teeth and worn dentitions. Throughout the paper, the supporting evidence for each rationale for partial-coverage restorations will be considered, as well as the risks and benefits of adopting an MI approach to indirect restorations.

Restoration of converging implants: Restorative complexity to facilitate retrievability

Implant treatment should be restoratively driven, however at times, ideal implant positioning may be sacrificed for surgical convenience at the expense of restorative complexity. A prosthesis incorporating a novel design was constructed to restore two converging implants placed in close proximity utilizing standard implant impression componentry and simple clinical stages. As the use of angulated screw channel technology was not possible, a customized cast “rest” abutment and overlying telescopic crown was fabricated that facilitated access for oral hygiene and retrievability as required. The complexity of the case design was transferred to the laboratory phases of construction. The case presented a satisfactory clinical outcome for an initially challenging implant presentation and reinforced the need to work closely with the laboratory technician.

Roles of Arbuscular Mycorrhizal Fungi on Plant Growth and Performance: Importance in Biotic and Abiotic Stressed Regulation

Arbuscular mycorrhizal fungi (AMF) establish symbiotic associations with most terrestrial plants. These soil microorganisms enhance the plant’s nutrient uptake by extending the root absorbing area. In return, the symbiont receives plant carbohydrates for the completion of its life cycle. AMF also helps plants to cope with biotic and abiotic stresses such as salinity, drought, extreme temperature, heavy metal, diseases, and pathogens. For abiotic stresses, the mechanisms of adaptation of AMF to these stresses are generally linked to increased hydromineral nutrition, ion selectivity, gene regulation, production of osmolytes, and the synthesis of phytohormones and antioxidants. Regarding the biotic stresses, AMF are involved in pathogen resistance including competition for colonization sites and improvement of the plant’s defense system. Furthermore, AMF have a positive impact on ecosystems. They improve the quality of soil aggregation, drive the structure of plant and bacteria communities, and enhance ecosystem stability. Thus, a plant colonized by AMF will use more of these adaptation mechanisms compared to a plant without mycorrhizae. In this review, we present the contribution of AMF on plant growth and performance in stressed environments.

The influence of prosthetic crown height and implant-abutment connection design selection on the long-term implant-abutment stability: A laboratory study

BACKGROUND AND AIM

Long-term edentulism associated with vertical loss of alveolar bone might lead to increased suprastructure height. This study aimed to evaluate the effect of suprastructure height on the stability of the implant-abutment connection by investigating the stability of two different two-piece titanium implants with internal hexagonal or conical connections under simulated oral loading conditions.

MATERIALS AND METHODS

A total of 48 specimens were used. The specimens were divided into 2 groups according to their implant-abutment connection (group H: internal hex connection, group C: conical connection). Each group was further divided into 3 groups according to the applied suprastructure height (H1; C1: 10 mm, H2; C2: 14 mm and H3; C3: 18 mm) (n = 8). All specimens were subjected to a cyclic loading force of 98 N for 5 million simulated chewing cycles. Then, all implants that survived the chewing simulation were quasi-statically loaded until failure. The monotonic-failure load and monotonic-bending moment at failure were evaluated.

RESULTS

After the dynamic chewing loading, the implants showed the following survival rates: group H: 95.8%; group C: 100%. The implant suprastructures revealed survival rates of 100% and 91.5% for groups H and C, respectively. After the artificial chewing simulation of 5 million cycles, some implants in the groups with higher crowns (14 mm and 18 mm) showed crack formation and plastic deformations under the light microscope. Regarding monotonic-failure load, implants with shorter suprastructures (10 mm) revealed higher resistance to failure (C1: 1496 and H1: 1201 N) than longer suprastructures (18 mm) (C3: 465 and H3: 585 N) which was expected. The mean monotonic-bending moment values at failure ranged from 400.7 Ncm to 673.3 Ncm.

CONCLUSION

Implant-supported restorations with increased crown height are considered stable for an extended time period (5 million cycles which equals approximately 20 years clinical service) and a reliable treatment option in case of increased inter-arch distance. There was no difference in stability of the two internal connections. Nevertheless, the integrity of implant components might be impaired when crowns with increased heights are applied.

Immunohistological composition of peri-implantitis affected tissue around ceramic implants-A pilot study

BACKGROUND

Aim of the pilot study was the histologic classification of the inflamed peri-implant soft tissue around ceramic implants (CI) in comparison with titanium implants (TI).

METHODS

Peri-implant tissue were retrieved from 15 patients (aged 34 to 88 years, seven males/eight females) with severe peri-implantitis (eight CI, seven TI). The peri-implant soft tissue samples were retrieved from the sites during scheduled removal of the implant and prepared for immunohistochemical analysis. Monoclonal antibodies (targeting CD3, CD20, CD138, and CD68) were used to identify T- and B-cells, plasma cells and macrophages. Quantitative assessment was performed by one histologically trained investigator. Linear mixed regression models were used.

RESULTS

A similar numerical distribution of the cell population was found in peri-implantitis around CI compared with TI. CD3 (TI, 17% to 85% versus CI, 20% to 70% of total cell number) and CD138 (TI, 1% to 73% versus CI, 12% to 69% of total cell number) were predominantly expressed. Notably, patient-individual differences of numerical cell distribution were detected. Co-localization of B- and T-lymphocytes was observed.

CONCLUSIONS

Peri-implantitis around CI in comparison with TI seems to have a similar histological appearance. Differences in cellular composition of peri-implantitis lesions might also depend on the patient's specific immune status and not only on the material used.

Novel bendable abutments as a solution to correct unfavorable implant inclination. A clinical report

OBJECTIVE

This clinical case report describes a novel bendable abutment as a prosthetic solution for implants presenting with an unfavorable inclination.

CLINICAL CONSIDERATIONS

A metal-ceramic screw-retained single crown was made on this novel bendable abutment in a patient presenting with a pronounced buccal inclination of an implant. A plastic reference guide is used to define the correct inclination and then this inclination is transferred to the abutment using a specific bending device at the same appointment.

CONCLUSIONS

Bendable abutments can be used as a solution to correct unfavorable implant inclinations. This abutment can be customized at the same appointment considering a case-specific inclination rather than conventional pre-angled abutments.

CLINICAL SIGNIFICANCE

Bendable abutments can be customized according to each case specificities while conventional pre-angled abutments may not be adequate for all patients. Also, the abutment customization could be easily done by dentists at their own practices using a specific bending device with hand pressure only, saving time, and the need to order pre-angled abutments or having it in stock.

Clinical and radiographic performance of one-piece and two-piece implant:a systematic review and meta-analysis

PURPOSE

The aim of this system review was to evaluate clinical and radiographic performance of one-piece implant (OPI) and two-piece implant (TPI).

METHODS

Electronic database searches were performed in MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and OpenGrey databases up to May 2019. Two authors individually screened the related literatures according to the inclusion and exclusion criteria. Main clinical outcomes included failure and complication rates. Radiographic outcomes were peri-implant bone loss between baseline and last available follow-up.

RESULTS

Finally, 11 articles reporting 10 different studies were included in this review. No statistically significant difference (P = 0.22) in risk of failure was found between the two types of implants (RR: 0.49, 95% CI: 0.16-1.53). Peri-implantitis accounted for most failures and complications and there was no statistically significant difference in risk of peri-implantitis no matter after 1 year follow-up (RR: 1.15, 95% CI: 0.37-3.53, P = 0.81) or at 2-3 years (RR: 1.95, 95% CI: 0.23-16.63, P = 0.54). With regard to the marginal bone loss (MBL) around implants, subgroup meta-analysis by platform switching versus platform matching showed a significant MBL-reducing effect for TPI when compared to OPI (WMD: 0.21mm, 95% CI: 0.07-0.36mm, P = 0.004) in the platform-switching subgroup, while no significant difference in MBL was observed between the two groups in the platform-matching subgroup (P = 0.67).

CONCLUSIONS

The results of this review suggested that OPI and TPI showed similar short-term survival rates and incidences of complications. Nevertheless, TPI with platform switching may be a better option to reduce peri-implant bone loss.

Retention of zirconia crowns to Ti-base abutments: effect of luting protocol, abutment treatment and autoclave sterilization

PURPOSE

To evaluate the influence of resin cement type, surface pretreatment and autoclave sterilization on the retention of Y-TZP crowns to Ti-base abutments.

METHODS

Y-TZP crowns were designed and milled to fit Ti-base abutments. Crowns were cemented using either a conventional resin cement (conventional) with a universal adhesive or a self-adhesive resin cement (self-adhesive), both following no surface pretreatment (No) or Ti-base abutment sandblasting (SB) (n=20/group). Half of the cemented samples were subjected to in-office autoclave sterilization. Pullout testing was performed in a universal testing machine at a speed of 1 mm/min until crown displacement. Data were statistically evaluated through a linear mixed model following post hoc comparisons by LSD test.

RESULTS

Pullout data as a function of cement type demonstrated higher retention for conventional relative to self-adhesive cement (p < 0.001). Ti-base sandblasting (SB) favored crown retentiveness over No pretreatment (p < 0.001). Sterilized crowns exhibited higher pullout values than non-sterile (p=0.036). All the two- and three-factor interaction analyses corroborated with the superior adhesive strength of conventional compared to self-adhesive cement (all, p < 0.011), as well as, SB relative to No pretreatment (all, p < 0.024). While autoclave sterilization maximized bond strength when self-adhesive cement (data collapsed over surface pretreatment, p < 0.050) and No pretreatment were evaluated (data collapsed over surface pretreatment, p < 0.013), no significant difference was observed for conventional resin cement (p=0.280) and SB (p=0.878) groups.

CONCLUSIONS

Conventional resin cement and/or Ti-base sandblasting increased Y-TZP crown retentiveness, with no significant influence of autoclave sterilization. Autoclaving increased retentiveness when self-adhesive cement and/or no Ti-base pretreatment were used.

A Prospective Clinical Cohort Investigation on Zirconia Implants: 5-Year Results

Mid-term data on zirconia oral implants is very rare. Therefore, the aim of this prospective clinical investigation was to evaluate the survival rate and the marginal bone loss of a one-piece zirconia implant after five years. Patient-reported outcomes were also recorded. Zirconia implants to support single crowns (SC) or a 3-unit fixed dental prosthesis (FDP) were placed and subsequently restored. After the insertion of the implants, at prosthetic delivery, and after five years, standardized radiographs were taken to evaluate marginal bone loss (MBL). For bone tissue evaluation, linear mixed models with random intercepts were fitted. Twenty-seven patients received one implant for an SC and 13 patients received two implants for a 3-unit FDP. Three patients each lost one implant for an SC before prosthetic delivery. Thirty-five patients were seen after five years, and no further implant was lost. The cumulative five-year implant survival rate was 94.3%. The MBL from implant installation up to five years was 0.81 mm. The MBL from implant installation to prosthetic delivery was statistically significant (p < 0.001). Patients perceived a significant improvement in function, esthetics, sense, speech, and self-esteem from pretreatment up to the five-year follow-up. The present findings substantiate the clinical applicability of this implant system.

Salivary Biomarkers and Their Application in the Diagnosis and Monitoring of the Most Common Oral Pathologies

Saliva is a highly versatile biological fluid that is easy to gather in a non-invasive manner—and the results of its analysis complement clinical and histopathological findings in the diagnosis of multiple diseases. The objective of this review was to offer an update on the contribution of salivary biomarkers to the diagnosis and prognosis of diseases of the oral cavity, including oral lichen planus, periodontitis, Sjögren’s syndrome, oral leukoplakia, peri-implantitis, and medication-related osteonecrosis of the jaw. Salivary biomarkers such as interleukins, growth factors, enzymes, and other biomolecules have proven useful in the diagnosis and follow-up of these diseases, facilitating the early evaluation of malignization risk and the monitoring of disease progression and response to treatment. However, further studies are required to identify new biomarkers and verify their reported role in the diagnosis and/or prognosis of oral diseases.

Five Degree Internal Conical Connection and Marginal Bone Stability around Subcrestal Implants: A Retrospective Analysis

BACKGROUND

There is limited information on the effect of the connection between subcrestally placed implants and abutments on marginal bone levels. The aim of the present retrospective study was to evaluate marginal bone levels after definitive prosthesis delivery around implants with an internal 5° conical connection placed in a subcrestal position.

MATERIALS AND METHODS

Patients treated with fixed prostheses supported by implants placed at a subcrestal level between 2012 and 2018 were recalled for a follow-up examination. All implants had 5° internal conical connection with platform switching. Radiographic marginal bone level (MBL) was measured. MBL change between prosthetic delivery (t₀) and follow-up examination (t₁) was calculated. A multiple regression model was performed to identify the most significant predictors on MBL change.

RESULTS

Ninety-three patients and 410 implants, with a mean follow-up of 2.72 ± 1.31 years, were examined. Mean MBL was -1.09 ± 0.65 mm and -1.00 ± 0.37 mm at t₀ and t₁, respectively, with a mean bone remodeling of 0.09 ± 0.68 mm. An implant's vertical position in relation to the bone crest, the year of follow up and the presence of type-2 controlled diabetes were demonstrated to be influencing factors for MBL modifications.

CONCLUSIONS

Subcrestally placed implants with platform switching and internal conical connection maintained stable bone levels over a mean follow-up of more than 2 years. How a tight internal conical connection between abutment and implant may contribute to this clinical evidence should be more deeply investigated. MBL variations seem to be mostly influenced by an implant's vertical position and presence of type-2 controlled diabetes.

Knowledge and Attitudes of Dental Interns and Dentists on Implants and Implant-Retained Restorations in Jeddah, Saudi Arabia

Objectives:

This cross-sectional study aimed to assess the knowledge and attitudes of dental interns and dentists in Jeddah, Saudi Arabia, about Cement-Retained Restoration (CRR), Screw Retained Restoration (SRR), and implant restoration.

Methods:

A total of 530 dentists and students participated in the study. Data were collected using a self-administrated questionnaire modified from previous studies. The collected data were analyzed using SPSS software for t-test, linear regression, and ANOVA.

Results:

Participants had a mean score of 5.01 (SD = 1.50) for a total of nine implant-retained restoration (IRR)knowledge questions (lowest score = 0, highest score = 9), and general implant knowledge had a mean score of 3.12 (SD = 1.25) for five questions with scores of 0 to 5. The participants’ knowledge about implants significantly differed in relation to gender, place of work, and work status. Also, participant knowledge about IRR showed significant differences in relation to participants' knowledge, age, gender and place of work. The dental interns and dentists were in agreement in considering SRR to be better than CRR for six out of nine factors. Those factors were cost effectiveness, expertise required for provision, retrievability, retention, fracture resistance, and passivity of fit.

Conclusion:

The overall knowledge of dental interns and dentists regarding implants and IRR was fair and needs to be improved, given the tendency of general dentists to engage in implant dentistry. Both dentists and interns considered CRR to be aesthetically superior, easier to fabricate, and requiring comparatively less expertise in comparison to SRR.

Efficacy of deep convolutional neural network algorithm for the identification and classification of dental implant systems, using panoramic and periapical radiographs: A pilot study

Convolutional neural networks (CNNs), a particular type of deep learning architecture, are positioned to become one of the most transformative technologies for medical applications. The aim of the current study was to evaluate the efficacy of deep CNN algorithm for the identification and classification of dental implant systems.A total of 5390 panoramic and 5380 periapical radiographic images from 3 types of dental implant systems, with similar shape and internal conical connection, were randomly divided into training and validation dataset (80%) and a test dataset (20%). We performed image preprocessing and transfer learning techniques, based on fine-tuned and pre-trained deep CNN architecture (GoogLeNet Inception-v3). The test dataset was used to assess the accuracy, sensitivity, specificity, receiver operating characteristic curve, area under the receiver operating characteristic curve (AUC), and confusion matrix compared between deep CNN and periodontal specialist.We found that the deep CNN architecture (AUC = 0.971, 95% confidence interval 0.963-0.978) and board-certified periodontist (AUC = 0.925, 95% confidence interval 0.913-0.935) showed reliable classification accuracies.This study demonstrated that deep CNN architecture is useful for the identification and classification of dental implant systems using panoramic and periapical radiographic images.

Incidence of retrograde peri-implantitis in sites with previous apical surgeries: A retrospective study

BACKGROUND

Retrograde peri-implantitis (RPI) is a rapidly progressing periapical infection that forms around the implant apex. It is usually associated with sites adjacent to teeth with apical lesions; previous endodontic failures, retained root fragments, etc. This study aimed to study the incidence of RPI in sites with a history of apical surgeries.

METHODS

Patients with sites treated for both apicoectomy and implant placement presenting to the University of Michigan School of Dentistry from 2001 to 2016 were screened. A total of 502 apicoectomies were performed, only 25 of these fit the predetermined eligibility criteria and were thus included in this retrospective analysis.

RESULTS

Implants that were placed in sites with a previous apical surgery had a cumulative survival rate of 92%. The incidence of peri-implantitis was 8%, while the incidence of RPI was 20%. There was an increased trend for RPI in cases where the cause of extraction was persistent apical periodontitis (35.7%), but this increase didn't reach the level of statistical significance (P = 0.061).

CONCLUSION

Implants placed in sites with previous apical surgery are not at an increased risk of implant failure or RPI.

Complications of Fixed Full-Arch Implant-Supported Metal-Ceramic Prostheses

We aimed to assess the biological and mechanical-technical complications and survival rate of implants of full-arch metal-ceramic prostheses, during five years of follow-up. 558 implants (of three different brands) retaining 80 full-arch metal-ceramic prostheses were placed in 65 patients, all of whom were examined annually for biological and mechanical-technical complications during the five years of follow-up. Descriptive statistics and univariate logistic regression were calculated. The cumulative survival rate of the implants was 99.8%, and 98.8% prosthesis-based. Mucositis was the most frequent of the biological complications and peri-implantitis was recorded as 13.8% at restoration-level, 16.9% at patient level and 2.0% at implant level. An implant length greater than 10 mm was shown to be a protective factor against biological complications. The mechanical-technical complications were associated with implant diameter, abutment/implant connection and retention system. Loss of screw access filling was the most frequent prosthetic complication, followed by the fracture of the porcelain. Full-arch metal-ceramic prostheses show a high prevalence of implant and prosthesis survival, with few biological and mechanical-technical complications.

A prospective study on the effect of coronal tooth structure loss on the 4-year clinical survival of root canal retreated teeth and retrospective validation of the Dental Practicality Index

AIM

First, to examine the impact of the residual volume of coronal tooth structure in posterior teeth measured with an intra-oral scanner on the 4-year clinical survival of root canal retreated teeth. Secondly, to assess retrospectively the effectiveness of the Dental Practicality Index (DPI) in predicting the survival of root canal retreated teeth.

METHODOLOGY

A total of 156 posterior root canal treated teeth (140 patients) had baseline periapical radiographs (PA) and cone-beam computed tomography (CBCT) scans taken prior to root canal retreatment. These teeth were followed up with a clinical examination at 1, 2, 3 and 4 years (T12, T24, T36 and T48) with periapical radiographs and CBCT images taken at T12, and PA taken at T24, T36 and T48 where appropriate. Root canal retreated teeth were dichotomized into 'survived' versus 'extracted'. Fisher's exact test was used to determine the association between the volume of remaining coronal tooth structure and the 4-year tooth survival. The Dental Practicality Index for each tooth was established using the preoperative clinical and radiographical data. Fisher's exact test was used to establish a relationship between categorical variables, the total score of DPI vs tooth outcome.

RESULTS

The percentage of extractions associated with teeth with <29.5% remaining coronal tooth structure was 3 times higher (12.5%) compared to that of teeth with a residual tooth structure > 29.5% (3.5%), but with no significant difference (P = 0.073). There was a significant correlation between the outcome of root canal retreatments at 1 year, assessed by both PA and CBCT, and the 4-year survival (Fisher's exact test, P = 0.007 and P = 0.001, respectively). Teeth with DPI scores ≥ 6 were more likely to be extracted than teeth with DPI score < 6 (18.8% vs. 3.9%) (Fisher's exact test, P = 0.045).

CONCLUSION

Teeth with <30% of remaining tooth structure were associated with a survival rate above 80% and teeth with more than 30% of residual tooth structure survived in more than 94% of the cases. The radiographic outcome of root canal treatment can also help to predict tooth survival with teeth having an unfavourable outcome at 1 year more likely to be extracted within 4 years of completion of treatment. The DPI score can potentially be used to identify teeth with failed root canal treatment, which are likely to be extracted following retreatment and cuspal coverage.

Proanthocyanidin-rich grape seed extract improves bone loss, bone healing, and implant osseointegration in ovariectomized animals

The purpose of the present study was to confirm if proanthocyanidin-rich grape seed extract (GSE) had the ability to improve bone health such as bone loss, bone healing, and implant osseointegration (defined as the direct connection between bone tissue and an implant) in ovariectomized (OVX) animals. We demonstrated that daily oral administration of GSE prevented bone loss in the lumbar vertebrae and femur in OVX mice. In addition, osteoclastogenesis in the lumbar spine bone of OVX mice, as assessed by histological and histomorphometric analyses, was accelerated but GSE prevented this dynamization, suggesting that GSE could counteract OVX-induced accelerated osteoclastogenic activity. In rats, OVX clearly impaired the healing of defects created on the calvaria, and GSE overcame this OVX-impaired healing. In the same way, osseointegration of a tibial implant in rats was retarded by OVX, and GSE counteracted the OVX-induced poor osseointegration, likely promoting bone healing by preventing imbalanced bone turnover. These results suggest that orally administered GSE improved implant osseointegration by mitigating the impaired bone health induced by OVX as a model of estrogen deficiency.

Bactericidal activity and recovery effect of hydroxyl radicals generated by ultraviolet irradiation and silver ion application on an infected titanium surface

This study investigated the bactericidal effect, the underlying mechanisms of treatment, and recovery of biocompatibility of the infected titanium surface using a combination treatment of silver ion application and ultraviolet-A (UV-A) light irradiation. Streptococcus mutans and Aggregatibacter actinomycetemcomitans were used in suspension and as a biofilm on a titanium surface to test for the bactericidal effect. The bactericidal effect of the combination treatment was significantly higher than that of silver ion application or UV-A light irradiation alone. The bactericidal effect of the combination treatment was attributable to hydroxyl radicals, which generated from the bacterial cell wall and whose yield increased with the silver concentration. To assess the biocompatibility, proliferation and calcification of MC3T3E1 cells were evaluated on the treated titanium surface. The treated titanium screws were implanted into rat tibias and the removal torques were measured 28 days post-surgery. The titanium surface that underwent the combination treatment exhibited recovery of biocompatibility by allowing cellular proliferation or calcification at levels observed in the non-infected titanium surfaces. The removal torque 28 days after surgery was also comparable to the control values. This approach is a novel treatment option for peri-implantitis.

Long term survival of mature autotransplanted teeth: A retrospective single center analysis

OBJECTIVE

The replacement of an irremediably compromised tooth requires an implant rehabilitation or a traditional fixed partial denture. In well-selected cases, a further therapeutic possibility is represented by tooth autotransplantation. Although dental transplants are poorly understood and practiced, the international literature agrees that it is considered the first choice when applicable. The advantages of this technique are numerous: use of an autologous element, maintenance of tissue trophism, aesthetic and functional restoration, costs reduction. Although autotransplantation is often performed with immature teeth, even mature teeth with fully formed apex can be used as donors. The aim of the present work was to analyze consecutive cases of completely formed donor teeth autotransplantations performed from 2005 to 2011 in 21 patients for evaluating the survival and success rate.

MATERIALS AND METHODS

The medical records of patients who underwent transplantation in a specialized center in Rimini (Italy) from 2005 to 2011 were checked. Only transplants of mature donor molars were considered. Patients were called up to evaluate the survival rate and success rate.

RESULTS

The mean age at the time of the surgery was 33,6 ± 7,4; mean follow up was 11,9 years ±1,9. Success rate at the time of latest recall visit was 80 % and survival 95 % of the analyzed cases.

CONCLUSIONS

The survival and success rate are in complete agreement with the most recent literature and confirm that the technique of autotransplantation is reliable when indications and protocols are rigidly followed, also using mature teeth as donors.

Dental implant maintenance teaching in Australia-A survey of education providers

INTRODUCTION

Implant treatments and peri-implant maintenance continue apace, while the evidence for implant maintenance and home hygiene continues to be developed. Information sources for dental practitioners and patients in peri-implant health maintenance and disease management are generally not known. This study investigated the implant maintenance topics taught, the discipline backgrounds of convenors and presenters and information delivery methods within implant dentistry teaching in Australia.

MATERIALS AND METHODS

An online survey was distributed to 56 convenors of implant dentistry and maintenance education programmes in Australia, garnering responses from 24 individuals which outlined 43 different education programmes.

RESULTS

Lectures were the main delivery method for implant maintenance information across the different course types. Peri-implant diagnostics were generally taught according to current literature recommendations, but coverage varied in topics where the evidence is yet to be established (eg home hygiene, professional maintenance and implant review). Some educators reported awareness of limitations in their programmes.

CONCLUSION

Implant dentistry education programmes in Australia vary widely in teaching implant maintenance, coverage of which should be current and evidence-based at all education levels. The structure of implant dentistry teaching at the continuing professional development level requires further development.

The Microbiome of Peri-Implantitis: A Systematic Review and Meta-Analysis

This review aimed to systematically compare microbial profiles of peri-implantitis to those of periodontitis and healthy implants. Therefore, an electronic search in five databases was conducted. For inclusion, studies assessing the microbiome of peri-implantitis in otherwise healthy patients were considered. Literature was assessed for consistent evidence of exclusive or predominant peri-implantitis microbiota. Of 158 potentially eligible articles, data of 64 studies on 3730 samples from peri-implant sites were included in this study. Different assessment methods were described in the studies, namely bacterial culture, PCR-based assessment, hybridization techniques, pyrosequencing, and transcriptomic analyses. After analysis of 13 selected culture-dependent studies, no microbial species were found to be specific for peri-implantitis. After assessment of 28 studies using PCR-based methods and a meta-analysis on 19 studies, a higher prevalence of Aggregatibacter actinomycetemcomitans and Prevotella intermedia (log-odds ratio 4.04 and 2.28, respectively) was detected in peri-implantitis biofilms compared with healthy implants. Actinomyces spp., Porphyromonas spp. and Rothia spp. were found in all five pyrosequencing studies in healthy-, periodontitis-, and peri-implantitis samples. In conclusion, the body of evidence does not show a consistent specific profile. Future studies should focus on the assessment of sites with different diagnosis for the same patient, and investigate the complex host-biofilm interaction.

Complication rates for various retention types in anterior implant-supported prostheses: A retrospective clinical study

STATEMENT OF PROBLEM

Implant-supported prostheses have typically been retained by cement or screws, each of which has advantages and disadvantages. Two new types of prosthesis with complementary advantages and disadvantages have been proposed: the screw- and cement-retained prosthesis, which combines cement and screw retention, and the antiloosening inner-post screw (ALIPS) type, which uses lateral screws. Both esthetic and functional factors should be considered for anterior prostheses; however, clinical studies of the complication rates of these designs are lacking.

PURPOSE

The purpose of this retrospective clinical study was to evaluate the complications of dental implant-supported restorations with various prosthetic types in the anterior region and to analyze other factors that affect complications.

MATERIAL AND METHODS

This study included 51 patients who had 83 implants placed in the anterior region by a single clinician between August 2009 and December 2016. Surgical and prosthetic features were recorded, and implant complications were analyzed.

RESULTS

There were 45 (55.4%) cement-retained implants, 5 (6.0%) screw- and cement-retained prosthesis implants, and 32 (38.6%) ALIPS-retained implants. Peri-implant mucositis was observed most frequently in the ALIPS type (21.9%), but the biological complications did not differ significantly with the prosthetic type. The most common mechanical complication was loss of retention in the cement type of prosthesis (30.4%) and screw loosening in the ALIPS type (43.8%). Implant complications varied with position (maxilla or mandible) and implantation timing (period from tooth extraction to implant placement).

CONCLUSIONS

The complications of implants placed in the anterior region were affected by different factors but did not differ significantly with the type of the retention.

Assessment of Peri-implant Buccal Bone Thickness Using Digital Imaging Techniques: A Systematic Review and Meta-analysis

Objectives:

This systematic review aimed to answer the following focused question: Do the currently available imaging techniques provide accuracy in the assessment of peri-implant buccal bone thickness?

Methods:

A search strategy was conducted in eight electronic databases, followed by an additional manual search in grey literature and references of selected articles. Studies evaluating the accuracy of imaging techniques to measure peri-implant buccal bone thickness were included. Individual risk of bias was assessed by the Quality Assessment Tool for Diagnostic Accuracy Studies-2 (QUADAS-2). Meta-analysis was performed to evaluate CBCT accuracy. The overall effect size was determined by means of the Z-test. Q test was used to evaluate the homogeneity of effect sizes among studies and I2 was applied to determine the variance within studies.

Results:

After an initial screening, 83 studies were further selected for full reading and 13 of them were considered eligible for this review. In sum, the accuracy of Cone-beam Computed Tomography (CBCT), of ultrasound, and of computed tomography were assessed. There was no statistically significant difference between CBCT and the gold standard (p=0.81). The mean difference between measurements of bone thickness obtained by CBCT and the goldstandard was -0.0.3mm [95%CI -0.29;0.253mm].

Conclusion:

CBCT showed acceptable accuracy for assessing peri-implant bone. No meaningful conclusion could be drawn about other techniques.

Clinical and patient-reported outcome of implant restorations with internal conical connection in daily dental practices: prospective observational multicenter trial with up to 7-year follow-up

Background

The interpretation of the results of randomized clinical trials is often questioned in relation with daily circumstances in practices. This prospective observational multicenter study was instigated to reflect the need for information in real-life situations with dental implants with internal conical implant-abutment connection (Conelog implant system). The implants were followed up at least 5-year post-loading; survival analysis (Kaplan-Meier), changes of soft tissue, and bone level over time, as well as patient satisfaction were evaluated.

Results

In total, 130 dental implants were placed in 94 patients (64 female, 30 male). Mean age of patients was 50.4 ± 13.7. At 5-year post-loading, 104 implants in 76 patients were available for evaluation. The cumulative implant survival rate was 96.6%. After an initial bone remodeling process post-surgery (bone loss of − 0.52 ± 0.55 mm), the bone level change remained clinically stable from loading to 5-year post-loading (− 0.09 ± 0.43 mm). Patient satisfaction surveyed by questionnaire (comfort, ability to chew and taste, esthetics, general satisfaction) steadily increased towards the end. At the last study follow-up, all the patients rated their general satisfaction as either very satisfied (87.5%) or satisfied (12.5%).

Conclusion

The study implants have shown to be highly effective with reliable peri-implant tissue stability over the 5 to 7 years of observation for both single tooth restorations and fixed partial dentures while used in standard conditions in daily dental practice. The results obtained are comparable with those obtained in controlled clinical trials.